My invention relates generally to door latches and more particularly to strike plates of spring actuated locking latches.
In recent years the number of burglaries has increased dramatically and, as a result, property owners have become increasingly interested in devices for preventing unauthorized entry. Many locking devices are available which cannot be easily jimmied but they are either excessively expensive or so inconvenient for authorized access that they are unacceptable to most potential users.
The spring loaded latch is widely used on doors in residences and office premises because of its convenience but, unfortunately, it is quite vulnerable to experienced burglars. With such simple tools as a pocket knife or credit card most burglars can gain access through a door with this type of latch faster than a person with a key. They accomplish this by inserting a card, knife blade or other thin, flexible object between the door jam stop and the door edge until it engages the latch bolt and then manipulate it until the bolt is pressed inwardly against its loading spring and access is accomplished.
The deadlocking spring latch which has a deadlock trip rod on one side of the latch bolt is designed to prevent this defect in spring latches, however, in many cases it is not mounted or maintained with sufficient care to provide this protection. The deadlocking spring latch only functions properly when the deadlock trip rod engages the strike plate. If the latch bolt is misaligned with the strike plate or the door can be moved to cause this misalignment, the deadlock does not operate. Spring bolt latches are also incorporated in panic bar hardware for fire and emergency exits where the same vulnerability to unathorized access exists.
Various devices have been suggested to overcome these difficulties but prior to my invention all have been either too expensive and complex, or not truly effective. A need, therefore, exists for a simple, inexpensive, yet truly effective device to make the spring bolt door latch burglarproof.
It is, therefore, a major object of my invention to provide an improved strike plate which renders spring bolt latches substantially burglarproof.
It is another object of my invention to provide an improved strike plate of the type described which will fit in the place of strike plates now in use without alterations to the door or jam.
Still a further object of my invention is to provide an improved latch plate of the type described which does not reveal its presence and, therefore, thwarts attempted countermeasures.
Yet another object of my invention is to provide an improved latch plate of the type described which is readily adaptable to a variety of door conditions and is simple to install and inexpensive to make.